Difference between revisions of "Team:CHINA CD UESTC/hp meetup"

The previous studies showed that the enzymatic biofuel cell (EBFC) has more advantages on operation and function over the ordinary biofuel cell (BFC). EBFC has three main advantages: 1) High efficiency of energy conversion; 2) Green alternative energy; 3) Characteristics fitted the biosensor. We found two high-efficiency oxidases, glucose oxidase and laccase, which can be used in anode region and cathode region of EBFC respectively. At the same time, we learned that laccase have some other advantages like ^[3] : 1) It comes from natural bacteria or plants, so it’s friendly to environment; 2) It has high-efficiency oxidability; 3) Laccase can oxidize a broad range of substrates so that it can be used in sewage disposal. It is definitely the most suitable choice to put laccase on the cathode.

Therefore, we set out to transform the cathode with laccase. For the purpose of visualizing the location and concentration of laccase, we combined RFP with laccase. After that, we designed a way of enriching laccase on the cathode--using magnetosomes！

Along with the development of times and population growth, energy consumption is increasing rapidly. Up to now, the thermal power is the main source. According to BP Energy Outlook 2035 , we can find that the world's fossil fuel reserves are declining ^[4] , and the largest shift of shares give us an insight into the most likely shape of the future energy landscape! (Figure 1)

Figure 1. There have been some rapid shifts in fuel shares in power generation in the past: oil gaining in the 1960s and losing in the 1970s; nuclear picking up in the 1970s/80s and falling in the 2000s; gas rising through the 1990s and 2000s. In the Outlook, the largest shifts are the increase in the renewables share and the decline in the coal share ^[4] .

Among numerous renewable energy, bioenergy is a kind of clean renewable energy and a potential excellent substitute for fossil fuel. With the advance of biotechnology biofuel cell (BFC) which can convert the chemical energy of fuel into electric energy with enzyme or microbial tissue as a catalyst, has been researched widely.

Previous iGEM teams had done some studies about microbial fuel cell (MFC). iGEM13_Bielefeld-Germany made an Escherichia coli Fuel Cell platform to provide an efficient electron transfer from the bacteria to the electrode. iGEM14_LZU-China cloned a NO3-sensor sequence and riboflavin producing genes into Escherichia coli for anode and a gene coding chromate (VI) reductase Yief was cloned into E.coli for cathode. iGEM14_SCAU-China boosted up the level of intracellular NAD+ for higher electron transfer rate.

Biofuel cell is divided into microbial fuel cell and enzymatic biofuel cell (EBFC). EBFC is a special kind of fuel cell which uses organics as fuels and enzymes as catalysts. EBFC is generally separated into anode region and cathode region by proton exchange membrane. Fuels are oxidized under the action of enzyme in the anode region. Oxygen is reduced in the cathode region.

EBFC have broad application prospect, so we want to create a new type of device to develop the bioenergy.

The main configurations of enzymatic fuel cells involve bioanodes based on glucose oxidase, glucose dehydrogenase or lactate oxidase and biocathodes based on copper oxidases such as laccase, tyrosinase or bilirubin oxidase. This concept was initiated by Mano et al. who implanted microbioelectrodes based on osmium redox hydrogels, in a grape obtaining thus 2.4mW at 0.54v ^[5] .

Laccases is a kind of copper-containing oxidoreductase. In the reduction reaction, the electron from the oxidation is transferred to the other three copper ions. These ions form a trinuclearic cluster, which transfers electrons to the terminal electron acceptor oxygen ^[6] .

Meanwhile, laccase has the property of oxidizing a wide range of substrates e.g., phenolic compounds, so it can be used in sewage disposal. Our project used these two enzymes and transformed the cathode. We constructed the expression vector of RFP + laccase and transformed it into E. Coli. The red fluorescence produced by RFP can be used as an indication of laccase’s concentration and activity. According to the method of electron transfer, EBFC can be divided into electronic media electrodes and direct electrochemical electrodes. Considered that the latter has high catalytic efficiency and small restriction by environment, we tried to enrich the laccase on the cathode to enhance the redox potential of our EFBC.

Figure 2. An electrochemical phenol biosensor based on the immobilization of laccase (Lac) on the surface of copper capped magnetic core–shell (Fe3O4–SiO2) nanoparticles (MNPs) ^[7] .

We obtained the laccase from BBa_K863005 . Traditional chemical approaches ^[7] of fixing laccase may affect the activity of laccase and are toxicological. So we hoped to find a better method!

Of course using synthetic biological methods is a great idea to achieve our goal. Magnetotactic bacteria (MTB), a kind of bacteria that can be attracted by magnet, are a superexcellent choice for us. We noticed that MTB contains a fantastic structure-- magnteosome. It is a magnetic nano materials covered by biofilm. And the magnetosome is essential to magnetotaxis.After our investigation, we decided to connect laccase to the magnetosomes’ membrane to enrich them on the cathode surface.

Figure 3. Transmission electron microscopy images of several different MTB showing their distinctive cell and magnetosome crystal compositions and morphologies. Scale bars = 500 nm in bacterial images and 100 nm in magnetosomes images ^[8] .

After our investigation, we decided to connect laccases to the magnetosome's membrane to gather them on the cathode surface.

But there are two problems for us to solve. On one hand, MTB are anaerobic, it means they are hard to be cultured. On the other hand, it is difficult to modify them. So, we were aiming to construct a magnetosome expression system in E.coli to solve those problems. According to a paper in Nature nanotechonlogy , we confirmed that transferring four related operons can make other bacteria magnetotactic ^[9] .

Finally, we co-transferred all the vectors we constructed to make E.coli produce magnetosomes carrying laccase. The special magnetosomes would be used into our EBFC to improve the electron transfer efficiency!

Purpose:

Publicity: With the development of iGEM, there is an increasing number of schools taking part in iGEM. In China, most teams are from northeast region, therefore, we want to expand the influence of iGEM in southwest China. This year the iGEM team of UESTC established the Southwest Union of China which was based on the colleges and universities in southwest region. We invited the teams that have taken part in or interested in iGEM as well as social organizations and enterprises related with biology to participate in our discussion.

Improvement: Universities and organizations of the union have their own strengths and characteristics. For example, social enterprises have different views, all the aspects of opinions are needed to be adopted. We expect each year in the future we can not only share and exchange different ideas about iGEM on communication live, but also exchange our projects online or in more forms, which will be a great help to future iGEM teams.

Details

This year our iGEM team spent a lot of energy on contacting with colleges and universities of southwest region, we successful got in touch with teams Taiwan's Chang Gung University and Sichuan University, as well as colleges expect to participate in iGEM next year, such as Sichuan Agricultural University and Southwest University for Nationalities, students from Chengdu Shude High School and Chengdu NO.7 High School Jia Xiang Foreign Language School who are interested in iGEM. In addition, we also invited several engineers and managers of the Chengdu Biological Maker. Finally we hold the iGEM communication and the Establishment of Southwest Union of China on July 25 at Qingshui river campus of UESTC.

Although the iGEM competition add the high school section since 2015. Chinese high school students have little enthusiasm to take part in iGEM. We consider it mainly from the pressure of China's College Entrance Examination, knowledge reserves, laboratory equipment, etc. But the most important reason is that they lack of a good understanding of iGEM and a more professional counseling. Therefore, we invited students from Chengdu Shude High School and Chengdu NO.7 High School Jia Xiang Foreign Language School who are interested in iGEM to attend our conference. During the conference, we introduced competition process to them in detail, and taught them some necessary experiment skills(High School Guide accessories). We hope that through this communication, high school students of the southwest can know about iGEM more comprehensive and arouse their enthusiasm to participate in iGEM.

In communication meeting, each universities actively shared their synthetic biology project and experience. Sichuan University introduced their project which is the technology of microbial nitrogen and carbon fixation. At the same time, they put forward their difficulty they are facing that they haven’t found a way to get the azotobacter. At the beginning of our project, we also spent a hard time on finding Magnetotactic Bacteria, so we suggest they can search relevant literatures to find research institutes’ email addresses and email them, or request school teachers to contact for help.

We showed our project of making a microbial fuel cell with Magnetotactic Escherichia coli. Our project aroused everyone’s attention and they were interested in the long gene cluster of Magnetotactic Bacteria. Software team of UESTC introduced minimal gene set prediction related software development from the perspective of bioinformatics. As the only software team among these teams, their project also attracted everyone’s interests.

Southwest University for Nationalities team was particularly interested in iGEM process and preparation conditions, because they were going to play their first game in the next year. Aiming at their most interesting topic, how to find a suitable project, we gave our suggestions. On the one hand, they can look for study angle based on research contents of school professional teachers. On the other hand, we expected that they can creating their project by combining their daily life experiments and literatures they read.

Sichuan Agricultural University team is also preparing to take part in iGEM next year; apparently they have some basic knowledge about iGEM. However, their biggest problem is the team sponsorship. For this problem, Biological Maker said that they would like to make further discussion with Sichuan Agricultural University students about the fund.

Representative of Biological Maker introduced Biological Maker culture and biology related enterprises region's situation as well as expressed their good will to cooperate with university students. In the subsequent activity, we went to the Biological Maker Space for visit and study.

After the further free discussions in terms of technology and ideas of iGEM, instructor Fengbiao Guo issued the Southwest Union of China certificate to each organization representatives and took a group photo as a souvenir. This not only marked the establishment of iGEM Southwest Union of China, but also indicated members of the union will start a more long-term and stable cooperation with each other.

Purpose:

Through the establishment of the University of Electronic Science and Technology iGEM club, we hope to achieve the following purposes:
1.Cooperate with the iGEM team to prepare the competition.
2. Offer a platform for the fresh students and junior students to get aware of iGEM.
3. The club is also a good place that create great idea about iGEM projects.

April 9th, the iGEM club of UESTC established in Shahe campus. We invited Mr. Dezhong Yao, Dean of School of Life Science and Technology, Lixia Tang, the instructor of CHINA_CD_UESTC, Fengbiao Guo, the instructor of software team.

The team leader of CHINA_CD_UESTC, Kaiyue Zhang introduced the iGEM and our team to the audiences. The leader of iGEM club, Huanhuan Wei said that the iGEM club will offer opportunities and the last information to the students who are interested in synthetic biology. There will be some interesting activities and interaction in this club. The members can start to prepare since the fresh year. They will know what to learn earlier and prepare well. The iGEM club will be a formal club like other clubs in our school. We will help it become our reserve forces.